boost/mpl/eval_if.hpp

0001
0002 #ifndef BOOST_MPL_EVAL_IF_HPP_INCLUDED
0003 #define BOOST_MPL_EVAL_IF_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2000-2004
0006 //
0007 // Distributed under the Boost Software License, Version 1.0.
0008 // (See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // See http://www.boost.org/libs/mpl for documentation.
0012
0013 // $Id$
0014 // $Date$
0015 // $Revision$
0016
0017 #include <boost/mpl/if.hpp>
0018 #include <boost/mpl/aux_/na_spec.hpp>
0019 #include <boost/mpl/aux_/lambda_support.hpp>
0020 #include <boost/mpl/aux_/config/msvc.hpp>
0021 #include <boost/mpl/aux_/config/gcc.hpp>
0022 #include <boost/mpl/aux_/config/workaround.hpp>
0023
0024 namespace boost { namespace mpl {
0025
0026 template<
0027       typename BOOST_MPL_AUX_NA_PARAM(C)
0028     , typename BOOST_MPL_AUX_NA_PARAM(F1)
0029     , typename BOOST_MPL_AUX_NA_PARAM(F2)
0030     >
0031 struct eval_if
0032 #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \
0033      || ( BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, >= 0x0300) \
0034         && BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, BOOST_TESTED_AT(0x0304)) \
0035         )
0036 {
0037     typedef typename if_<C,F1,F2>::type f_;
0038     typedef typename f_::type type;
0039 #else
0040     : if_<C,F1,F2>::type
0041 {
0042 #endif
0043     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,eval_if,(C,F1,F2))
0044 };
0045
0046 // (almost) copy & paste in order to save one more
0047 // recursively nested template instantiation to user
0048 template<
0049       bool C
0050     , typename F1
0051     , typename F2
0052     >
0053 struct eval_if_c
0054 #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \
0055      || ( BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, >= 0x0300) \
0056         && BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, BOOST_TESTED_AT(0x0304)) \
0057         )
0058 {
0059     typedef typename if_c<C,F1,F2>::type f_;
0060     typedef typename f_::type type;
0061 #else
0062     : if_c<C,F1,F2>::type
0063 {
0064 #endif
0065 };
0066
0067 BOOST_MPL_AUX_NA_SPEC(3, eval_if)
0068
0069 }}
0070
0071 #endif // BOOST_MPL_EVAL_IF_HPP_INCLUDED